/* 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;
using System.Linq;
using Lucene.Net.Documents;
using Document = Lucene.Net.Documents.Document;
using Directory = Lucene.Net.Store.Directory;
using IndexInput = Lucene.Net.Store.IndexInput;
using IndexOutput = Lucene.Net.Store.IndexOutput;
using RAMOutputStream = Lucene.Net.Store.RAMOutputStream;

namespace Lucene.Net.Index
{
    
    sealed class FieldsWriter : IDisposable
    {
        internal const byte FIELD_IS_TOKENIZED = (0x1);
        internal const byte FIELD_IS_BINARY = (0x2);
        [Obsolete("Kept for backwards-compatibility with <3.0 indexes; will be removed in 4.0")]
        internal const byte FIELD_IS_COMPRESSED = (0x4);
        
        // Original format
        internal const int FORMAT = 0;
        
        // Changed strings to UTF8
        internal const int FORMAT_VERSION_UTF8_LENGTH_IN_BYTES = 1;
                 
        // Lucene 3.0: Removal of compressed fields
        internal static int FORMAT_LUCENE_3_0_NO_COMPRESSED_FIELDS = 2;
        
        // NOTE: if you introduce a new format, make it 1 higher
        // than the current one, and always change this if you
        // switch to a new format!
        internal static readonly int FORMAT_CURRENT = FORMAT_LUCENE_3_0_NO_COMPRESSED_FIELDS;
        
        private readonly FieldInfos fieldInfos;
        
        private IndexOutput fieldsStream;
        
        private IndexOutput indexStream;
        
        private readonly bool doClose;
        
        internal FieldsWriter(Directory d, System.String segment, FieldInfos fn)
        {
            fieldInfos = fn;
            
            bool success = false;
            String fieldsName = segment + "." + IndexFileNames.FIELDS_EXTENSION;
            try
            {
                fieldsStream = d.CreateOutput(fieldsName);
                fieldsStream.WriteInt(FORMAT_CURRENT);
                success = true;
            }
            finally
            {
                if (!success)
                {
                    try
                    {
                        Dispose();
                    }
                    catch (System.Exception)
                    {
                        // Suppress so we keep throwing the original exception
                    }
                    try
                    {
                        d.DeleteFile(fieldsName);
                    }
                    catch (System.Exception)
                    {
                        // Suppress so we keep throwing the original exception
                    }
                }
            }
            
            success = false;
            String indexName = segment + "." + IndexFileNames.FIELDS_INDEX_EXTENSION;
            try
            {
                indexStream = d.CreateOutput(indexName);
                indexStream.WriteInt(FORMAT_CURRENT);
                success = true;
            }
            finally
            {
                if (!success)
                {
                    try
                    {
                        Dispose();
                    }
                    catch (System.IO.IOException)
                    {
                    }
                    try
                    {
                        d.DeleteFile(fieldsName);
                    }
                    catch (System.Exception)
                    {
                        // Suppress so we keep throwing the original exception
                    }
                    try
                    {
                        d.DeleteFile(indexName);
                    }
                    catch (System.Exception)
                    {
                        // Suppress so we keep throwing the original exception
                    }
                }
            }
            
            doClose = true;
        }
        
        internal FieldsWriter(IndexOutput fdx, IndexOutput fdt, FieldInfos fn)
        {
            fieldInfos = fn;
            fieldsStream = fdt;
            indexStream = fdx;
            doClose = false;
        }
        
        internal void  SetFieldsStream(IndexOutput stream)
        {
            this.fieldsStream = stream;
        }
        
        // Writes the contents of buffer into the fields stream
        // and adds a new entry for this document into the index
        // stream.  This assumes the buffer was already written
        // in the correct fields format.
        internal void  FlushDocument(int numStoredFields, RAMOutputStream buffer)
        {
            indexStream.WriteLong(fieldsStream.FilePointer);
            fieldsStream.WriteVInt(numStoredFields);
            buffer.WriteTo(fieldsStream);
        }
        
        internal void  SkipDocument()
        {
            indexStream.WriteLong(fieldsStream.FilePointer);
            fieldsStream.WriteVInt(0);
        }
        
        internal void  Flush()
        {
            indexStream.Flush();
            fieldsStream.Flush();
        }
        
        public void Dispose()
        {
            // Move to protected method if class becomes unsealed
            if (doClose)
            {
                try
                {
                    if (fieldsStream != null)
                    {
                        try
                        {
                            fieldsStream.Close();
                        }
                        finally
                        {
                            fieldsStream = null;
                        }
                    }
                }
                catch (System.IO.IOException)
                {
                    try
                    {
                        if (indexStream != null)
                        {
                            try
                            {
                                indexStream.Close();
                            }
                            finally
                            {
                                indexStream = null;
                            }
                        }
                    }
                    catch (System.IO.IOException)
                    {
                        // Ignore so we throw only first IOException hit
                    }
                    throw;
                }
                finally
                {
                    if (indexStream != null)
                    {
                        try
                        {
                            indexStream.Close();
                        }
                        finally
                        {
                            indexStream = null;
                        }
                    }
                }
            }
        }
        
        internal void  WriteField(FieldInfo fi, IFieldable field)
        {
            fieldsStream.WriteVInt(fi.number);
            byte bits = 0;
            if (field.IsTokenized)
                bits |= FieldsWriter.FIELD_IS_TOKENIZED;
            if (field.IsBinary)
                bits |= FieldsWriter.FIELD_IS_BINARY;
            
            fieldsStream.WriteByte(bits);
            
            // compression is disabled for the current field
            if (field.IsBinary)
            {
                byte[] data = field.GetBinaryValue();
                int len = field.BinaryLength;
                int offset = field.BinaryOffset;
                    
                fieldsStream.WriteVInt(len);
                fieldsStream.WriteBytes(data, offset, len);
            }
            else
            {
                fieldsStream.WriteString(field.StringValue);
            }
        }
        
        /// <summary>Bulk write a contiguous series of documents.  The
        /// lengths array is the length (in bytes) of each raw
        /// document.  The stream IndexInput is the
        /// fieldsStream from which we should bulk-copy all
        /// bytes. 
        /// </summary>
        internal void  AddRawDocuments(IndexInput stream, int[] lengths, int numDocs)
        {
            long position = fieldsStream.FilePointer;
            long start = position;
            for (int i = 0; i < numDocs; i++)
            {
                indexStream.WriteLong(position);
                position += lengths[i];
            }
            fieldsStream.CopyBytes(stream, position - start);
            System.Diagnostics.Debug.Assert(fieldsStream.FilePointer == position);
        }
        
        internal void  AddDocument(Document doc)
        {
            indexStream.WriteLong(fieldsStream.FilePointer);

            System.Collections.Generic.IList<IFieldable> fields = doc.GetFields();
            int storedCount = fields.Count(field => field.IsStored);
            fieldsStream.WriteVInt(storedCount);
            
            foreach(IFieldable field in fields)
            {
                if (field.IsStored)
                    WriteField(fieldInfos.FieldInfo(field.Name), field);
            }
        }
    }
}